reisjdmd

i had an 0107 code [which going by memory is lean a/f bank1, sensor 1]. my mechanic replaced that sensor with a denso unit. however, the code returned after a few miles. he checked for a vacuum [none] leak, and cleaned the maf sensor. so, he suggested we replace the bank 2, sensor 1. however, when he tried too remove it, no matter what he tried, the threads started to come off with the sensor. so, i have 2 problems:
why do i still have a 0107 code
are there any tricks to removing the bank 2, sensor 1.
will i have to buy a new bank 2 exhaust manifold??

salimshah

First, bank 2 is near radiator (front) .... [just in case #1 and #2 are mixed up].

If the threads are hosed, you have to buy a new manifold or take it to a machine shop and see if they can build the threads [put in an adapter, braze and re-thread, helicoil?]

If you dig, you will see Lexmex posted picture on the repair job he did.

Salim

code58

No, I think you may need a new mechanic. Where did he get that DTC? That should be a "P" code (generic) None of the Lexus specific codes begin with 0, only the P codes. That code says "Manifold Absolute Pressure/ Barometric Pressure Circuit low input" This should give you an explanation of that code and what to do. http://www.obd-codes.com/p0107 No wonder it didn't get rid of the light.
Additionally, the ONE thing I know of that will positively loosen a seized nut or bolt is HEAT! Meaning an acetylene torch. You heat around the outside of the threads till a dull red (that expands the threads) and move QUICKLY to remove the seized nut/ bolt. Sometimes if it is rusted/ seized badly it may need to be heated a 2nd time to get the 2 parts apart. The problem you have is if he has already started to tear the threads loose, that MAY not work. The second thing is, the manifolds are made of stainless steel and stainless is very much prone to "galling". That means you have to be careful and always make sure threads on or in stainless are clean and (if necessary) lubed. It may be difficult to save them at this point but they could likely have been saved if a torch had been used initially when it didn't give. I'm surprised the mechanic didn't know that. I'm from rust country and anyone in automotive work knows that is the only way to get a truly seized thread loose.
For future reference this is an excellent site for help with DTC's. http://www.obd-codes.com/trouble_codes/lexus/
There's a lot to this site, just have to wander it to see.
You MAY have to do what Lexmex di to replace the threads, but shouldn't have to replace the manifold. I'm puzzled about being able to replace the B1S1 sensor without problem and the B2S1 is seized. It's virtually always the oposite of that. You are aware that B2S1 is the FRONT sensor, right?

reisjdmd

code 58

it was p0171 [i forgot to add the lettter P]; he did replace the rear sensor [called bank1, correct?]; he did use heat around the front sensor [called bank 2, correct?]. the threads are coming off with the front sensor. i guess i will have to replace the front manifold. i think this is called the LEFT/driver's side manifold, correct? i don't want to order the wrong one. the used parts sites refer to right/passenger side and left/driver's side. i would have said front and back, but what do i know. anyway, i need the manifold that sits near the radiator, which i assume is bank 2/front/left/driver's side. they are $100 or less, used. am i correct in naming this? thanks for the information.

salimshah

All the confusion starts with transverse mounted engine. In good old days (RWD) the engine front was the front of the vehicle and the cylinder closets to the front pulley was #1.

With transverse the sides are now front and the back. When the engine is out of the bay then every one starts calling them driver side or the passenger side.

To cut the confusion follow this>

Cylinder 1,3,5 are next to the firewall and that side is the Bank1.
Cylinder 2,4,6 are next to the radiator and that side is Bank2.

Before going for the ultimate solution (new manifold), check with the machinist to see if he can do insitu repair. You should avoid making it a larger project.


Salim
ps: Some mechanics would tell you upfront that there is a chance of threads going bad and they will get your skin in the risk. After breaking the bind, I always wiggle the bolt (sensor) and unthread by hand, If you had gone over the past posts, I also recommend 1/4 turn loose and 1/8 turn tight action. If you use the wrench all the way and feel resistance then some thing is wrong.

Code has given good advice, but both his and mine may be too late.

Baetke

Salim, Code58
Do you guys recommend application of penetrating oil to the sensor threads before attempting removal?
Lexus dealership replaced 2 exhaust manifolds on my RX because they couldn't get the sensor out. Next time it needs done I will attempt myself and I have more patience then they do, especially if I can avoid damaging the threads.

Baetke

tarzan17

I just changed both A/F sensors using two applications of Aerokroil, 6hrs between each and then let sit overnight. Bank2 sensor (closest to rad) was easy to remove and I could see/smell Aerokroil on the threads once removed. Bank1 was different story, had to use torch to remove. Applying penetrating oil as step one is agreed way to tackle removal of those sensors. I was careful not to contaminate new sensors by touching the hole and applying anti-seize (which comes with the Denso sensors) on the threads.

salimshah

It is a matter of odds. When I replaced my bank1 sensor ... I was concerned, but for me the sensor came off with ease.

Then there are horror stories too.

I would suggest to move on and get the repair done. Also do not waste time with jb-weld (it does not keep up with high exhaust temp). Apply the antiseize as you put it back.


Salim

code58

I believe he should have used Aerokroil as Tarzan said. It is one of the best penetrating oils made.
I guess the best way to describe the correct manifold would be "left side, one in front by the radiator in a transverse mounted engine". If they get that wrong, I don't know what to say. Send 'em back to the 5th grade I guess. That is indeed Bank 2. Still trying to figure out how he got A/F ratio sensor out of code P0107 ??? (P0171 ???)

reisjdmd

my mistake. i was going by memory after speaking to him on the phone. it was actually p0171. the bank1, sensor 1 [rear] was changed to a new denso unit. the system was checked for vacuum leaks. the maf sensor was cleaned with electrical cleaner. the car still does exactly the same thing. after it reaches operaing temperature, the cel comes on [p0171] and the car stutters badly at anything over about 45 mph. however, and this is interesting, the stuttering goes away when the pedal is presssed down for true acceleration. it only stutters with very light pedal pressure on a flat surface when going over about 45 mph, like we all do in order to maintain a steady speed. i'm going to give the maf sensor a very good cleaning myself today. if, after a very good cleaning, i see any signs of improvement, i will replae the maf sensor. if there is no improvement, i return it to the shop and we start from scratch. he still thinks it might be a good idea to replace the bank 2 sensor 1, and, since i have already purchased it, i would be happy with that. however, there is the problem of a stuck sensor as in my first post above. drats!!! drats!!! problems, always problems.